This invention relates to prefabricated forming elements for construction of reinforced concrete building walls, and methods of wall construction employing those elements.
Conventional forming for poured reinforced concrete walls employed heavy plywood panels clamped and nailed into place with tie rods between parallel panels to prevent them from spreading apart under the hydraulic forces. The plywood was treated so that it could be stripped away after the concrete had set. If the wall was to be insulated, insulation would then be fastened to one or both faces of the concrete. Rigid foam plastic panels have been shown to be strong enough to substitute for plywood. It has the distinct advantage that it may be left in place after pouring to serve as permanent rigid insulation for the wall.
U.S. Pat. No. 5,040,344 issued Aug. 20, 1991 to Durand discloses a foam panel forming system. Horizontal T beam stiffeners fit into slots cut in the panels. Vertical shores are attached to the stiffeners on one side and ties join the stiffeners of one side to the stiffeners of the second side. This is a costly and labor intensive system, panels must be especially prepared for the stiffeners.
U.S. Pat. No. 4,936,540 issued Jun. 26, 1990 to Boeshart teaches tie elements which may be forced through the panels, and walers which may then be attached to the outboard ends of the ties. He also teaches the ties supporting horizontal reinforcing rods. This is a labor intensive system with no provision being made for maintaining vertical alignments of overlying or adjacent panels.
The DIAMOND SNAP-FORM.TM. Expanded Polystyrene Concrete Forming System provided by AFM corporation of Excelsior, Minn. provides a special molded tie which holds the inner and outer faces of the two parallel foam panels in secure spaced apart relationship. These ties fit into slots specially cut in the long edges of the panels spaced one foot apart in 1.times.8 foot panels. These ensure horizontal and vertical alignment of the panels and the tie portion between panels is provided with molded support for horizontal reinforcing rods. It requires that the panels have slots cut in the edges every foot. It provides no support between the ties, relying instead on the strength and integrity of the foam edges to hold the fluid concrete in place. The system limits the pour to four feet. For higher walls, repeat pours must be made after the lower portion has set to reduce hydraulic pressure on the panels at their edges.